Fasting equates to deep rest. I don't believe you can strength train while resting. Health improves during rest and fasting.Think of your metabolism as being something like your car's use of gasoline. Miles per gallon vary slightly, based upon efficiency of use, but mpg will remain the same, day in and day out, if you go the same speed. Your body cannot defy the laws of thermodynamics and spare fat while exercising, just because you didn't eat.